Practice Test Geeks(EETC) Electrical Technician Certification Practice Test
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Power Distribution Flashcards

7 cards from real EETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What is the standard color code for the high-voltage 'B' phase conductor in a North American overhead distribution system?

    Answer: Blue

    In the standard A-B-C phase color convention, A=black, B=red, and C=blue for medium-voltage overhead distribution, though utility practices may vary.

  2. Which protection scheme is most appropriate for detecting a single-line-to-ground fault on an ungrounded distribution system?

    Answer: Zero-sequence voltage (59N) or ground fault detectors

    On an ungrounded system, fault current is very small and does not flow back through neutral, so zero-sequence voltage detection or capacitively coupled ground fault detectors are used.

  3. The 'demand factor' of an electrical installation is defined as:

    Answer: The ratio of the maximum demand to the total connected load

    Demand factor equals maximum demand divided by total connected load, indicating that not all connected loads operate simultaneously at full rated capacity.

  4. Which NEC article primarily governs the installation of service-entrance conductors for a residential customer?

    Answer: Article 230

    NEC Article 230 covers services, including service conductors, service entrance equipment, and service disconnects.

  5. A power distribution transformer is rated 500 kVA, 13,200/480V. What is the rated full-load secondary current?

    Answer: 601 A

    Full-load secondary current = kVA × 1000 / (√3 × V) = 500,000 / (1.732 × 480) ≈ 601 A.

  6. What is the purpose of a neutral grounding resistor (NGR) connected in the neutral of a distribution transformer?

    Answer: To limit ground fault current while allowing fault detection

    An NGR limits ground fault current to a safe level (typically 5–400 A) while still allowing enough current to operate protective relays and detect faults.

  7. Which type of distribution substation configuration provides the highest reliability by allowing continuous operation even if one transformer fails?

    Answer: Secondary selective network

    A secondary selective network with multiple transformers and normally open tie breakers allows immediate load transfer to alternate transformers if one fails, ensuring uninterrupted service.